<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .leftDiv{
            width: 100px;
            height: 100px;
            background: green;
            float: left;
        }
        .normalDiv{
            height: 100px;
            background: pink;
            /* 添加 overflow: hidden , 触发BFC */
            overflow: hidden;
        }

        .container {
            background-color: blue;
            /* 添加 overflow: hidden , 触发BFC */
            overflow: hidden; 
        }
        .container div {
            float: left;
            background-color: lightgreen;
            margin: 10px;
        }
    </style>
</head>
<body>
    <!-- <div class="leftDiv"></div>
    <div class="normalDiv"></div> -->

    <div class="container">
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
        <div>Sibling</div>
    </div>

    <div style="height: 100px;width: 100px;float: left;background: lightblue">
        我是一个左浮动的元素 one
    </div>
    <div style="width: 200px; height: 200px;background: grey">
        我是一个没有设置浮动,也没有触发 BFC。
    </div>
     
    <div style="height: 100px;width: 100px;float: left;background: lightblue">
        我是一个左浮动的元素 two
    </div>
    <div style="width: 200px; height: 200px;background: grey;overflow:hidden">
        我是一个没有设置浮动,触发 BFC 元素。
    </div>
</body>
</html>